A new category of lap siding, made from fiber cement or composite wood materials, has been introduced into the residential and light commercial siding market during the past ten or more years. It has replaced a large portion of the wafer board siding market, which has been devastated by huge warranty claims and lawsuits resulting from delamination and surface irregularity problems.
Fiber cement siding has a number of excellent attributes which are derived from its fiber cement-base. Painted fiber cement looks and feels like wood. It is strong and has good impact resistance and it will not rot. It has a Class 1(A) fire rating and requires less frequent painting than wood siding. It will withstand termite attacks. Similarly composite wood siding has many advantages.
Fiber cement is available in at least 16 different faces that range in exposures from 4 inches to 10.75 inches The panels are approximately 5/16 inch thick and are generally 12 feet in length. They are packaged for shipment and storage in units that weigh roughly 5,000 pounds.
Fiber cement panels are much heavier than wood and are hard to cut requiring diamond tipped saw blades or a mechanical shear. Composite wood siding can also be difficult to work with. For example, a standard 12 foot length of the most popular 8¼ inch fiber cement lap siding weighs 20.6 pounds per piece. Moreover, installers report that it is both difficult and time consuming to install. Fiber cement lap siding panels, as well as wood composite siding panels, are installed starting at the bottom of a wall. The first course is positioned with a starter strip and is then blind nailed in the 1¼ inch high overlap area at the top of the panel (see FIG. 1). The next panel is installed so that the bottom 1¼ inch overlaps the piece that it is covering. This overlap is maintained on each successive course to give the siding the desired lapped siding appearance. The relative height of each panel must be meticulously measured and aligned before the panel can be fastened to each subsequent panel. If any panel is installed incorrectly the entire wall will thereafter be mis-spaced.
The current fiber cement lap siding has a very shallow 5/16 inch shadow line. The shadow line, in the case of this siding, is dictated by the 5/16 inch base material thickness. In recent years, to satisfy customer demand for the impressive appearance that is afforded by more attractive and dramatic shadow lines virtually all residential siding manufacturers have gradually increased their shadow lines from ½ inch and ⅝ inch to ¾ inch and 1 inch.